1. Field of the Invention
The present invention relates to an improved rotor drive assembly for a rotor in a centrifugal liquid processing apparatus for separating whole blood into components thereof and for automatically collecting one of the components.
2. Description of the Prior Art
Heretofore various apparatus have been proposed for separating whole blood into at least three components thereof in a centrifugal liquid processing apparatus where a rotor assembly having a container or bowl for receiving the whole blood to be processed by centrifugation is rotated in the apparatus to cause separation of the whole blood into red blood cells at the outer radius, a buffy coat of white blood cells at an intermediate radius and plasma containing platelets at an inner radius of the container. Outlets are provided on the container at the different radius and tubings are connected to the outlets. Pumps are provided for withdrawing each of the blood components which collects at one of the radii and at a zone adjacent each of the outlets. The outlets are coupled to the tubings either directly or by means of a fluid seal. When they are connected directly, twisting is prevented by reason of the rotor assembly being driven at a speed twice the speed of a coaxial member mounting a cable holding device through which the tubings pass to reach the bowl in the rotor assembly. As a result of the different speeds of the coaxial member and the rotor assembly, twisting is prevented. A further explanation of an apparatus having such an arrangement can be found in U.S. Pat. No. 3,986,442.
In the prior U.S. Pat. No. 3,986,442 there is disclosed a drive mechanism for a centrifugal liquid processing apparatus which includes a lower drive shaft which is driven at the bottom thereof by a prime mover. At the upper end of the lower drive shaft is mounted a rotor drive assembly including a first plate which is journaled to the lower drive shaft. An idler shaft is rotatably journaled in the plate and has a lower pulley. A belt engages the lower pulley and an upper pulley is provided on the idler shaft and two idler pulleys depend from a second plate which is spaced above and fixed to the first plate and rotates therewith. An upper hollow drive shaft is rotatably journaled to the second plate and has a driven pulley at the lower end thereof. A continuous belt engages the upper pulley on the idler shaft, the idler pulleys and the driven pulley at the lower end of the upper drive shaft, all of which together form a planetary drive means.
Containers for centrifuging blood are positioned within a bowl fixed to the upper end of the hollow upper drive shaft. With this arrangement an umbilical cable containing flexible tubings extends through a tubular sleeve mounted to the upper second plate, through the space between the first and second plates and upwardly thrugh the hollow upper drive shaft for connection to the containers in the bowl.
As will be described in greater detail hereinafter, the improved rotor drive assembly of the present invention differs from the rotor drive assembly described above by providing for a unitary vertical drive shaft as opposed to a lower drive shaft and an upper hollow drive shaft and with a different arrangement of pulleys.